The present technology relates to a solid-state image sensor, represented by a CMOS (complementary metal oxide semiconductor), on which ordinary imaging pixels and focus detection pixels are two-dimensionally arrayed, and a camera system.
An example of a known focus detection technology is pupil division phase difference.
In a pupil division phase difference method, the amount of defocus of an imaging lens is detected by dividing the light beams passing through the imaging lens to form a pair of divided images, and detecting pattern deviation between this pair of divided images.
A solid-state image sensor applying such a pupil division phase difference method is described in, for example, JP 2008-103885A and JP 2007-103590A.
The solid-state image sensor described in JP 2008-103885A is formed from a two-dimensional array of imaging pixels having a photoelectric conversion unit and focus detection pixels that have pairs of a first photoelectric conversion unit and a second photoelectric conversion unit.
Further, at an output unit, as illustrated in FIG. 1, a signal obtained by adding the respective outputs from the first photoelectric conversion units 11 and 21 of a first focus detection pixel 1 and a second focus detection pixel 2 that are adjacent to each other is output from the first focus detection pixel 1. Similarly, a signal obtained by adding the outputs from the second photoelectric conversion units 21 and 22 is output from the second focus detection pixel 2.
Namely, the solid-state image sensor described in JP 2008-103885A has two photoelectric conversion units for one focus detection pixel (AF pixel). Further, the charge signals from the photoelectric conversion units forming a focus detection pair are added at a floating diffusion layer, which is an output node.
The solid-state image sensor described in JP 2007-103590A is formed from a two-dimensional array of first pixel cells 3 as illustrated in FIG. 2(A) and second pixel cells 4 as illustrated in FIG. 2(B).
The first pixel cells 3 include a first photoelectric conversion unit 31 that generates charges based on incident light.
The second pixel cells 4 include an optical element (microlens) that collects incident light and second photoelectric conversion units 42 and 43 that generate charges based on the light collected by the optical element.
A solid-state image sensor configured so that the focus detection pixels are larger than the ordinary imaging pixels is also described in JP 2007-127746.